Pulverizing mill



June 22 1926.

1,589,741 L. c. BON'NOT ET AL PULVERI ZING MILL Filed Nov. 4, 1925 4Sheets-$heet 2 v I I Jwumtou L.CB0IZ7Z0LZ W 53 f1. flarker @MPULVERIZING M 4 hoet 5 File 1925 June 22 1926.

L. C. BONNOT ET AL PULVERI ZING. MILL Filed Nov. 4, 1925 4 Sheets-Sheet4 gmmw Z. 6130222205 2 Mflffiarz r Patented June 22, .1926.

UNITED STATES LOUIS C. BORN-'1, OF LOUISVILLE, AND WILLIAM H. BARKER,

a 1,ss9,741 PATENT OFFICE.

or CANTON, 0310,.-

srenons TO THE BONNOT commemorcannon, oman coaronsrron or 01110;

Application filed November The invention relates to a rotary drumgrinding or pulverizing mill partly filled with balls or other grindingmedia for the vide a machine of this character having means forpreventing the grinding media from being thrown or drawn into the fan ofthe se arator and damaging the same, and provlded with an exhaust conein the discharge end of the mill, leading to the separator, and. havingspiral fins and a receding, concave, peripheral flange, for plowing ordeflecting and repellingthe balls and coarse material away from the coneand continually forming a furrow in the ball mass adjacent to theperipheral flange for receiving among the balls any coarse materialwhich is by-passedfrom the exhaust separater and returned through thenozzle in the cone to the mill. 0 Also, to provide means for returningto the drum any coarse; material which may; be thrown 'or drawn into,the cone; to provide for a decreased suction at the exhaust side of thedrum and an increased suction in the exhaust end of the cone by means ofthe diflz'erence in area of the opposite ends of the cone, in order tocarry. only the finely pulverized portions of material into the inletend of the cone; the increased velocity, at the outlet end of the coneserving to quickly exhaust the fine material through the exhaustseparator and providing suflicient velocity to preventthe fine materialfrom settling in the passages and obstructing the same: thedecreased,ve-.

locity at the exhaust side of the drum, however, being sufiicient tocarry thefinely pu1- verized material out of the drum and .prevent thesame from settling in the mill and cushioning the balls.

And finally, to provide a bypass and centrifugal separator exhauster, tocreate a counterdraft through the nozzle into the TCOIIB for returningto the drum oversized material segregated by the exhaust separator aswell as to clear the, cpne of any'coarse material. which may at theoutlet side of the 4, recs. Serial no. 66,855.

deposited therein by the grinding action; thus making a completeseparation of the finely pulverized material and eliminating thenecessity of using an'independent cycle separator'or other separatingapparatus.

The lmproved mill is well adapted for pulveriz'ing small lump orslackcoal foruse in furnaces or powdered fuel feeding systems, but 1t shouldbe understood that it is equally well adapted for ulverizing othercoarse or granular materia s. y

The present improvement also contemplates the elimination of the usualaxial tube or center ipe extending into and sometimes throught e drum,in air swept mills, the raw material being fed referably through aninlet cone and througi an axialopening into one end of the drum, aperforate bafile plate in the center of this opening breaking thesuction through the axial center of the drum. The drum is preferablysupported upon flanged rollers journaled upon a shaft, and is providedwith a ring gear meshing with a driving pinion carried in an adjustablebearing. I m An embodiment of the improved pulveriz- 1ng mill isillustrated in the accompanying drawings, forming part thereof, inwhich- Figure 1 is an axial section through the improved mill;

Fig. 2, a section on line 22,-.Figure 1;

Fig. 3, a section on line 3-3 Figure 1;

Fig. 4, a vertical section through the centrifugal exhaust separator,and

Fig. 5, a fragmentary section on the line 55, Figure. 1, showing theaction of the spiral finsand counter-current from the exhaust separator.7

Similar numerals of reference indicate correspondingtparts. i

The grindin drum 10 is mounted upon the flanged rol ers 11 which arejournaled G upon the shaft 12, and is arranged to be .driven through thering gear, 13 carried upon the drum, and the driving pinion 14, mesh-100 ing therewith, and-j'ournaled upon brackets/ 15 arrangedto'be'adjustably mounted upon the supporting base 16 as by the bolts "17ahd adjustin screw 18.

The in at end of the drum may be provided 106 with the axial feedcone-19, and a perforate disk 20 is mounted in the o enin thereof andconnected to the en wall of'the cone as" byx-ra'dial wings 201 .andbolts 21.

.The periphery of this disk is spiaedzfromthe no.

ofthebase periphery of the feed opening of the drum, as shown at 22,permitting the greater part of the material to be fed around and beneaththe disk into the drum, while the perforate disk permits a portion ofthe air to be drawn axially through the drum, breaking the direct axialdraft from the feed inlet tothe exhaust cone and preventing any but thevery finest particles of the material from being carried directly intothe outlet or discharge cone of the drum.

r The discharge or exhaust cone 23 is connected to the discharge end ofthe drum as by the peripheral flange 24 and bolts 25. Thisdischarge-cone may be provided with a lining formed of segmentalsections 26 provided with the spiral fins 27, the inner ends of whichare spaced from each other near the small end of the cone and the outerends of the fins preferably extend over the angles of the peripheral rimflange 28 and terminate in the receding annular groove '29 formed in"said flange. v

The discharge cone exhausts into the dis charge neck 30, which isconnected to the inlet opening of the centrifugal fan chamber 31 of theexhaust separator and is preferably provided with an angularly dis osedscreen 32, of substantially coarse mes to deflect any balls'which may bethrown into the same.

An exhaust impeller 31 is located within the fan casing 31 and isarranged to be ro-' tated as by the motor 33. An outlet pipe 34communicates with the fan casing for carrying away the finely pulverizedmaterial which is exhaustedfrom the drum.

A by-pass 35 communicates with the outlet side of the fan casing andextends be= neath the pan 36 in the discharge neck 30, saidvpan having adeflecting flange 37 substantially parallel with the bottom wall of thedischarge cone and forming a nozzle arranged to project a blast of airinward along the bottom wall of the cone.

This centrifugal-fan by-pass construction has three functions; first, itacts asa centrifugal separator, segregating the over size material whichis drawn into the exhaust separator and providing a passage for the.return of the same to the mill for regrindmg; second, it sets up acounter-current of air from the end of the nozzle, through the exhaustcone, that tends to prevent the coarse material from being drawn intothe cone;

and third, it continually cleans the walls of the cone from any coarsematerial which may be deposited thereon;

As a consequence the capacity of the mill s greatly increased becausesuificient suction 1s maintained to withdraw all of the fine material assoonas the same is pulverized to the proper mesh, while the greaterportion of the coarser material is repelled from entermg the exhaustcone, and any small pore of the discharge centage of the coarse materialwhich is carried into the exhaust cone by the gradually essity of acyclone separator or other independent separating apparatus.

With this construction, the material. to be pulverized is passed fromthe inlet cone, around the periphery of the perforate plate 20, and onlythe very finest material is carried through the "perforations andaxially through the drum to the exhaust cone.

The material is thrown varound in the drum with the balls 38 bycentrifugal action, pulverizing 'the material, and only the very finestparticles thereof are, exhausted through the fan, as the area of thelarge end cone is several times greater than the area of the dischargeend thereof, providing a comparatively low velocity of suction at thelarge end of the cone, which will pick up only the very finest terial,and a greatly accelerated velocity of suction at the discharge end ofthe cone, quickly clearing the same of the fine particles of material.

particles of macharge into connecting bins with such uniformity as notto require any grading or classifying. I

The balls and coarse material are repelled from entering the large mouthof the discharge cone and are prevented from riding up upon the wallsthereof by means of the annular groove 29 and the spiral fins 27, and

coarse material is further repelled and prevented from being carried upalong the walls of the cone by means of the counter air current abovedescribed, while any balls which may be thrown into the exhaust neckwill strike the screen 32 and be returned to the drum by the abovedescribed means.

The means for preventing grinding balls from entering the fan and theforate disk in the feed opening, which are illustrated and described buti not claimed herein, are made the subject matter of parent application,Serial No. 47,039, filed July 30, 1925, by these applicants.

-We claim: i =1 1. A material pulverizing millincluding a rotary drumwit grinding media therein, a feed opening in one end of the drum and anaxial discharge cone flared inward formin an outlet opening extendingfrom the other end of the drum, the mouth formed by the larger end ofthe cone being substantially unobstructed, means impelling a current ofair through the drum from the inlet to the outlet ereof, and peripheralmeans repellingthe entrance of grinding m dia and coarse use of a perlmaterial into the mouth of the discharge 2. A material pulverizing millincluding a ml rotary drum with grinding media therein, a [6 feedopening in one end of the drum and an axial discharge cone flared inwardforming an outlet opening extending from the other end of the drum,means impelling a current of air through the drum from the inlet to 10the outlet thereof, and means repelling the entrance of grinding mediaand coarse madrum, means impe ling a current of air through the drumfrom the inlet to the outlet thereof, and spiral fin's on the interiorof the discharge cone extending over the rim flange thereof.

4.- A- material pulverizing mill including a rotary drum with grindingmedia therein, a feed opening in one end of the drum and an axialdischarge cone flared inward forming an outlet opening extending fromthe other end of the drum, means impelling a current of air through thedrum from the inlet to a the outlet thereof, means repelling theentrance of grinding "mediaand coarse material into the mouth of thedischarge cone, said means including an outwardly flared rim 40 flangeconnectin the large end of the discharge cone wi the peripheralportionof v the drum, and spiral finson the'interior of thedischarge coneextending over the rim thereof. p

5. A material pulverizing. mill including arotary drum with grindingmediatherein,

a feed opening in one end of the drum and an axial discharge cone flaredinward form ing an outlet opening extending from the other end of thedrum, means'impelling a current ofair through the drum from the inlet tothe outlet thereof, means repelling the entrance of grinding media andcoarse material into the mouth of the discharge cone, and a nozzle inthe discharge end of the cone projecting a current of air inwardly alongthe bottom wall thereof.

6. A pulverizing mill including a rotarydrum with grinding vmediatherein, a discharge cone flared inward at the discharge on end of thedrum and'having a peripheral, angularly flared rim flange provided withan annular groove for deflecting the grinding media away from theentrance to the. cone.

7. A pulverizing mill including a rotary drum with grinding mediatherein, a dis charge cone flaredinward at the discharge end of the drumand having a peripheral, angularly flared rim flange provided with anannular groove, and spiral fins on the in terior of the cone extendinginto the annular groove for deflecting the grinding media away from theentrance to the cone.

8. A pulverizing mill including a rotary drum with grindlngmediatherein, a discharge cone'fla-red inward at the discharge end ofthe drum, anexhauster separator communicating with'the discharge cone, a

return air discharge nozzle in the discharge end, of. the cone and avby-pass from the outlet sideof the exhauster separator to the nozzle.

'9. A pulveiizing mill including a rotary drum with grindlng mediatherein, a di'scharge cone flared inward at the discharge end of thedrum, an exhauster separator commumcatmg with the discharge cone, areturn air discharge nozzle in the discharge-end of the cone, 9. by-passfrom the outlet side of a the exhauster separator to said nozzle and adeflecting flange upon the nozzle spaced from the walls of the cone. Intestimonythat we claim the above, we have hereunto subscribed our names.

, Louis 0'. BONNOT. WILLIAM M. BARKER.

